One of the biggest factors into shot speed, as far as a hockey sticks go, will be matching your shot strength and speed to your hockey stick flex.

Lower the flex (65 - 90) more whipping action with each shot, which will increase your shot speed if your shot strength is average or lower. Although you will be able to increase your shot speed your accuracy will be decreased.

If you have average or greater shot strength, a higher stick flex (100+) will give you a much more accurate shot, but will require more energy to create the whipping action necessary to generate higher shot speed.